If I remembered correctly, you needed team of 3 to take a part in Chunin exam. Who was Sakura's teammates? Also, who was Ino & Choji's teammate? Since Shika already became a Chunin. Ten Ten, Rock Lee & Neji could have tested together again. Kiba, Hinata & Shino could have tested together again. In my personal opinion, once you have passed the 2nd exam, you can be exempt from taking a test again, you just need recommendation from other jounins & chunins & decision made by Hokage.